JSPuzzles: If you like jigsaw puzzles, this is the site to visit. The program slices up a picture into pieces, and lets you put it together. You can even upload your own photos to be made into puzzles.

TypeRacer: Test your typing speed and race against other people at the same time!

Renaissance Kingdoms: Basically an online Renaissance Faire, this game does its best to replicate life in early modern Europe. Be a peasant, a lord, a politician, or an innkeeper, and everything in between.